Abstract: By using a quasi-geostrophic barotropical model,five numerical experiments whose integration times are longer than 120h are performed in order to investigate the effects of interactions between the tropical cyclone circulation and smaller scale vorticies embedded within it on its structure and movement.Results show that the interactions can creat the irregular evolutions of the asymmetric structures of the tropical cyclone,which may cause track meanders of 100km on time scales of a day,and abrupt changes of the directions and velocities of the tropical cyclone motion,and that the effects of the interactions may change obvioursly when the smaller scale vorticies are embedded in variours positions to the tropical cyclone.